Availability

Definition

Availability is the time a system remains operational and accessible to users. It is typically expressed as a percentage of uptime over a defined period (e.g., monthly or yearly).

The DevOps Maturity Model explicitly lists Availability as one of the key metrics for measuring DevOps maturity.

Availability SLAs

Common availability targets:

Availability	Downtime/Year	Downtime/Month	Downtime/Week
99%	3.65 days	7.31 hours	1.68 hours
99.9%	8.76 hours	43.83 minutes	10.08 minutes
99.99%	52.60 minutes	4.38 minutes	1.01 minutes
99.999%	5.26 minutes	26.30 seconds	6.05 seconds

Across DevOps Maturity Levels

Maturity	Availability Capability
Phase 1	Poor — reactive monitoring, siloed teams, manual processes cause frequent outages
Phase 2	Improving — essential monitoring detects issues, but manual intervention required
Phase 3	Better — automated infrastructure reduces human errors, faster recovery
Phase 4	High — continuous monitoring for early detection, root cause analysis capability
Phase 5	Max uptime — no interruptions to customer experience, rapid data-driven decisions

Key Practices for High Availability

Architecture

Redundancy at every layer
Load balancing
Geographic distribution
Graceful degradation
Circuit breakers

Operations

Continuous monitoring
Automated failover
Disaster recovery planning
Regular maintenance windows
Capacity planning

Development

Robust error handling
Idempotent operations
Transaction management
Feature flags for rapid rollback
Chaos engineering

Relationship with Other Metrics

Metric	Relationship with Availability
MTTD	Faster detection = shorter outage = higher availability
MTTR	Faster recovery = shorter outage = higher availability
Error Budget	Availability target defines the error budget
Change Failure Rate	Fewer failed deployments = fewer outages = higher availability
Scalability	Better scalability prevents availability degradation under load

Sources

sources/devops-maturity-model-from-traditional-it-to-advanced-devops.md

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